Manufacture of coated articles



April 16, 1946. w. J. MALCOLMSON ET AL 2,398,712

MANUFACTURE OF COATED ARTICLES Filed Sept. 4, 1942 IN V EN TORS WJ. MHLCOLMSON 1 MIA/E2 E By ylw H TTOENEY an article.

area. 2

. Patented Apr. 1*6,

UNITED Md 'm'ac'ruim F coa'rnn narrows William J. Malcolmson, Riverside, and Robert V.

- 1Miner, Westem' Springs, 111., assignors to Western Electric Compahmlncorporated, New York, N. Y a corporation of New York lication September 4,1942, SerialNo. 457,324 I coated articles and moreparticularly to an article V having an; adherent coating of noble f metal on itsfsurface and to a method of making such an article.

It iswsometimes-desirable' to providean-article with a-coating which will ,beboth corrosion resistant and conductive. Certain metals, such as gold, silver and platinum,'have been used for this 4 purpose.

.An' object, of this invention is to provide an article having a noble metal coating and an efmethod for producing such fective and eillcient In accordance with one embodiment of this with the carbon.

va Claims. *(01. 20 4-48) invention relates to 'the' manufacture of and to restrict their use to the portions of the. are actually in contact electrode surface which An organic gold compound suitable'for coating in accordancewith this invention may be prepared in several ways,- An organic gold compound having the empiricalformula CmHuSAuCla may be prepared by mixing. terpenewith sulheavy metals mayalso be used instead of the gold invention, an article madeof'aluminum is first anodized and then coated with a liquid organic gold compound. The coated article is-then fired to decompose the compound and-tolea've a thin gold film on the coated'area. r r

. In accordance with another embodiment of this invention, an article may be provided with a coat-' 'ing of aluminum, the aluminum anodized and chloride, according to; the metal coating desired.

cosity with an essential oil, such, for example. as oil of lavender or, rosemary oil. A suitable compound may also be prepared by heating an essential oil containing a saturated alcohol or ester, such as terpeneo'l, with sulphur. This mixture is then purified by distillation at from 120,

C. to 130 C. .under. 20 mm. pressure. The purithen coated with aliquid organic gold compound.

The coated article is fired and the compound decomposes, leaving a thin gold fllm on the coated Other objects. and advantages of this invention scription taken in conjunction with the following drawing: 3

Fig.1 shows an enlarged plan view of a transmitter electrode c'oz'itedlin accordance with-one embodiment of this invention, and I Fig. '2 is a sectional view of thesame. taken in many instances, satisfactoryperformance of the apparatus necessitates that these. contact members receive transmitted current without appreciable loss or distortion. 1 "For example, in certain types of telephone transmitters, cup shaped With anessential oil.

be apparent from the following detailed defled productis then caused to react with a 10% aqueous solution of gold chloride mixed with res-' mates of bismuth, rhodium and chromium. The product is then diluted to the desired viscosity In practicing this invention, an article such as a transmitter electrode 3, shown in Fig. 1,- made "of aluminum is anodized by electrolizlng it with 'a bath of sulphuric acid or by any other suitable to aluminum anodizing method.- This produces a finely porous surface 4 to-which the coating to be subsequently applied adheres'excellently. The area which it is desiredto coat'is then coated either by brushing-or spraying with aouantity of gold compound, or other noble metaL'prepared 'as described above, the thickness of the coatingv being determined largely by the viscosity of the 40 pound and leave a thin,-'adherent film 5 of noble metal as a coating on the "anodized electrodes are usedto provide the necessary 'electrical connections with the'carbon particles therein and satisfactory operation of the transmitter depends 'inlarge measure upon the contact emciency .of these electrodes. In order to provide the needed operating and service characteristics,

'itis often'.'deslrable to, use gold. or some other noble metal as a contact-material on these electrodes and, due to the very highcost' of these noble metals, it is desirable to app y ethin aluminum surface.

Ithas been found that with some organic gold compounds, such as diethylmonobromogold, the compound will decompose 'fairly rapidly at room temperatures. However, using a gold compound prepared by'the reaction of sulphur on terpenes as described above, it has been found desirable to'use temperatures between 300 C. and 600 C. to'accelerate the-rate, of decomposition. However, temperatures up to the melting point of the aluminum may be usedif desired, since gold, silver and platinum have meltingipoints subst'an- The compound may be diluted to the desired vis- In coating articles other than articles of aluminum, in order to obtain an adherent coating of gold, or other noble metal, it has been found desirable to provide the article with a coating of anodized aluminum prior to coatingwith the organic gold compound. In this way, any article may be provided with an adherent coating of gold or other noble metal. A

While this invention has been described in connection with coating with gold, the method is equally applicable to coating with other noble metals such as platinum or silver, an organic compound of either being used as the coating material. While but two embodiments of this invention have been described, it will be.understoo d that many changes and modifications may be made therein without departing from the spirit or scope of the present invention.

What is claimed is:

1. A method of producing an article having a coating of noble metal which comprises providing the article with a base coating of aluminum having an anodized surface, coating the article with an organic compound of a salt of a noble metal, and then heating the coated article to decompose the compound.

' pound of asalt of a noble metal, and then heating the article to between 300C. and 600 0. to decompose the compound.

4. A method of producing an article or aluminum having a coating of noble metal thereon comprising anodizing the surface of the article, coating the article with an organic gold salt compound, and then heating the coated article to decompose the compound.

5. A method of producing an article of aluminum having a coating of noble metal thereon comprising anodizing the surface of the article, coating the article with an organic goldcompound, and then heating the article to between 300 C, to 600 C. to decompose the compound.

6. A method of producing an article of aluminum having a coating of noble metal thereon, comprising anodizing the surface of the article, coating the article with a solution of diethylmonobromogold, and then decomposing the compound by the application of heat to leave a gold coating.

7. A method of producing an article having an aluminum surface with a coating of a noble metal which comprises anodizing the aluminum surface, applying an organic compound of a salt of said metal to the anodized surface, and decomposing said compound by the application of heat to leave a coating of said metal on said surface.

8. A method of obtaining a thin adherent film of gold on an article comprising providing the article with a surface of anodized aluminum, coating the article with an organic gold compound having the empirical formula CroHrsSAllCla, and then heating the coated article to decompose the compound. 4

' WILLIAM J. MALCOLMSON.

ROBERT V. MINER. 

